Pyroxasulfone shows a high level of herbicidal effect on weeds of Poaceae family, including Echinochloa crus-galli var. caudata, Digitaria ciliaris, Setaria viridis, Poa annua, Sorghum halepense, Alopecurus myosuroides, Lolium multiflorum (Italian ryegrass), Lolium rigidum (rigid ryegrass), Avena fatua, Beckmannia syzigache, wild oat and the like; as well as weeds with broad leaves, including Persicaria lapathifolia, Amaranthus viridis, Chenopodium album, Stellaria media Stellaria, Abutilon avicennae, Sida spinosa, Sesbania exaltata, Ambrosia artemisiifolia, Ipomoea nil, Galium spurium var. echinospermon, Veronica persica, Veronica hederifolia, Lamium amplexicaule, Viola mandshurica and the like; and perennial and annual weeds of Cyperaceae family, including Cyperus rotundus, Cyperus esculentus, Kyllinga brevifolia Rottb. var. leiolepis, Cyperus microiria, Cyperus iria and the like. Moreover, pyroxasulfone is known to have a herbicidal effect on a broad spectrum of weeds.
However, when pyroxasulfone is used at an upland field for foliage treatment, it sometimes causes phytotoxicity to useful crops and useful plants such as fruit trees, vegetables, flowering plants, and trees, including Triticum aestivum, Hordeum vulgare, Secale cereale, Zea mays, Sorghum bicolor, Glycine max, Brassica rapa, Carthamus tinctorius, Helianthus annuus, Linum usitatissimum, Arachis hypogaea, Sesamum indicum, Solanum tuberosum, Ipomoea batatas, Allium cepa, Allium sativum, Beta vulgaris, cotton plants, mint plants, lawn plants and the like, so that the usage of pyroxasulfone had been limited to soil treatment.
Because of this, an agrochemical composition for foliage treatment at an upland field having a high level of safety to those useful crops and useful plants and a herbicidal effect on a broad spectrum of weeds had been desired as an agrochemical active ingredient comparable to pyroxasulfone.
On the other hand, a microencapsulation technology for agrochemical active ingredients is known and, for example, Non-patent Documents 1 discloses microcapsules of various useful chemical compounds, including an agrochemical active ingredient, which microcapsules use different types of materials for their wall members, and the manufacturing procedure thereof.
However, microencapsulation of an agrochemical active ingredient has conventionally aimed in general to control dissolution of the agrochemical active ingredient. Because dissolution of an agrochemical active ingredient from an agrochemical composition, including dissolution of an agrochemical active ingredient from microcapsules, is always mediated through water in a farm field, the microencapsulation of an agrochemical active ingredient has been considered to be a useful technology in an environment, such as paddy field, which is rich in water. Accordingly, the microencapsulation of an agrochemical active ingredient has been considered so far to be difficult to be technically applicable to a farm field, such as upland field, which is short of water. That is, there has been heretofore little knowledge of an agrochemical composition, which has been microencapsulated intended for a phenomenon other than dissolution control, and particularly any formulation technology, which also enables foliage treatment by microencapsulation of pyroxasulfone applicable for soil treatment has not been known at all.